Low-Pressure Carburizing Patents: Who Leads, Gaps 2026
- Filing peaked in 2018 at 12 records and has not returned to that level since, even before accounting for publication lag on the most recent years.
- One assignee leads with 16 records against a fifth-place count of 2 and a tenth-place count of 1 — a steep drop-off after the top of the ranking.
- Coating and surface deposition classes dominate C23C appears in 44.2% of the 43 records in scope, ahead of core heat-treatment class C21D at 37.2%.
What this landscape covers
This review maps 43 published records matching low-pressure carburizing and high-pressure gas quenching process claims, filed between 2015 and mid-2026. The search string targets core process terms — acetylene boost-diffuse cycles, intergranular oxidation control, quench severity, cycle time, and the use of helium or nitrogen as quench media — rather than generic heat-treatment language, so the set is narrow by design.
Records are drawn from receiving offices spanning Europe, the United States, China, India, Canada and Italy, giving a reasonably international view of where applicants choose to file rather than only where they invent.
Filing trend and technology composition
The two charts below use the same 43-record denominator throughout, so class shares can be compared directly even though a single record can carry more than one IPC class.
Filing trend, 2017–2026
Filings rose to a peak of 12 in 2018 and have since declined; 2026 is a partial year and, per the usual 18-month publication lag, its true count will not be visible for some time. Growth rate is not stated here because fewer than four complete years remain once that lag is factored in.
IPC subclass distribution
C23C (coating and surface deposition) and C21D (heat treatment of metals) are the two largest classes, followed by C22C (alloys) and B22F (powder metallurgy). Furnace-hardware classes F27D and F27B, along with C22F and H01M, each appear in a small minority of records, marking the outer edge of where this search string picks up adjacent equipment and materials work.
Shares are the percentage of the 43 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Low-Pressure Carburizing and Gas Quenching with Eureka
This page is one run against one query. Ask Eureka your own question about low-pressure carburizing and gas quenching and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records in this set
CA2364356A1 — Process and apparatus for high pressure gas quenching in an atmospheric furnace
Apparatus and process for recycling a quenching gas, such as helium, to be used with a treating gas, such as a carburizing gas, for the treating of components in an atmospheric furnace.Filed by Praxair Technology, Inc.; part of a family that also produced the two most-cited records in this set.
View full record| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | EP1211329A2 | Process and apparatus for high pressure gas quenching in an atmospheric furnace | 25 |
| 2 | US20020104589A1 | Process and apparatus for high pressure gas quenching in an atmospheric furnace | 17 |
| 3 | CN106939371A | 一种消除内应力提高超高强度钢薄壁工件尺寸精度方法 | 14 |
| 4 | US7967920B2 | Method and measurement system for the control of an active charge surface in the low pressure carburizing pro… | 14 |
| 5 | WO2016041977A1 | A pre-alloyed iron- based powder, an iron-based powder mixture containing the pre-alloyed iron-based powder a… | 13 |
| 6 | EP1980641A2 | Method and measurement for the control of an active charge surface in the low pressure carburizing process | 9 |
| 7 | US20170275740A1 | Pre-alloyed iron- based powder, an iron-based powder mixture containing the pre-alloyed iron-based powder and… | 7 |
| 8 | US10465268B2 | Pre-alloyed iron-based powder, an iron-based powder mixture containing the pre-alloyed iron-based powder and … | 7 |
| 9 | CN101481783A | 硬质合金双室高压气淬工艺方法 | 7 |
| 10 | US20080277029A1 | Method and measurement system for the control of an active charge surface in the low pressure carburizing pro… | 5 |
Citation counts inside this corpus skew toward older filings; treat them as a signal of influence on later filers, not as a measure of current commercial relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns stand out once the records are broken down by class, geography and time.
One applicant holds a wide lead
The top-ranked assignee sits at 16 records against a fifth-place figure of just 2 and a tenth-place figure of 1. That gap suggests a single applicant built out a broad process and equipment portfolio early, while the rest of the ranked field filed in small, often single-record increments.
Surface coating claims lead over core heat treatment
C23C (coating and surface deposition) appears in a larger share of records than C21D (heat treatment of metals proper, 37.2%). That points to a corpus weighted toward the diffusion and surface-chemistry side of carburizing rather than furnace-cycle mechanics alone.
Activity has cooled since 2018
The trend climbs from 4 in 2017 to a peak of 12 in 2018, then falls off toward 2026. Because publication lags filing by roughly 18 months, the last one to two years understate true filing activity, but the multi-year decline before that lag window is a genuine signal.
Filing is split evenly across Europe and the US
Europe (EPO) and the United States each account for 10 records, with China at 6 and India, Canada and Italy trailing behind. That even EPO/US split indicates applicants are protecting the same inventions in both regions rather than favouring one home market.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to low-pressure carburizing and gas quenching, with the prior art for and against each one.
Who is filing, and where the field is thin
The ranked field covers 16 companies in total — this is the complete ranking the dataset returns, not a top-50 or top-100 cut. Momentum data shows the leading assignees, including the largest filer, all recorded 0 filings in the latest year, consistent with the broader post-2018 slowdown.
A single applicant dominates the ranked field
The top assignee's 16 records dwarf the rest of the ranking, built in part on the high-pressure gas quenching family that also produced this set's most-cited documents. Its latest-year filing count is 0, matching the wider cooldown across the ranked leaders.
Collaboration is rare and small in scale
Only three co-assignee pairs appear in the dataset, each linked by a single shared record. That points to a field of mostly independent filers rather than joint-venture or consortium-style development.
No tracked assignee filed in the most recent year
Every assignee named in the recent-momentum data, including one with a -100% year-on-year change, recorded zero filings in the latest year. Given publication lag, this likely reflects incomplete recent-year data as much as a genuine stop in R&D.
| Assignee | Recent year | YoY |
|---|---|---|
| SECO/WARWICK S.A. | 0 | — |
| Hoganas AB | 0 | — |
| Praxair Technology, Inc. | 0 | — |
| Yingpu (China) Co., Ltd. / Precision Castparts (Yingpu) | 0 | — |
| Henan Northern Hongyang Electromechanical Co., Ltd. | 0 | — |
| L'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude | 0 | -100% |
| Jiangsu Rufei Bearing Technology Co., Ltd. | 0 | — |
| Etudes et Constructions Mecaniques | 0 | — |
Where to take this next
The landscape points to a mature core process with several thinner adjacent branches still open to new claims.
Check freedom-to-operate around the leading family
With one applicant holding 16 of the ranked records, and its family producing the two most-cited documents in this set, a claim chart against that portfolio is the first step before filing new gas-quenching process claims.
Run a freedom-to-operate check in EurekaWatch the furnace-hardware and non-ferrous edges
F27B, F27D, C22F and H01M each cover a handful of records at most. These are the classes where a well-drafted first claim has the least prior art to design around.
Explore white space in EurekaTrack whether filing recovers post-2018
The decline since the 2018 peak, combined with a zero-filing latest year across tracked assignees, could mean the field has consolidated around existing patents or that recent filings simply have not published yet.
Set up a filing-trend alert in EurekaCommon questions on this landscape
Low-pressure carburizing runs the carbon-diffusion step in a furnace held below atmospheric pressure, typically using acetylene as the boost gas, which avoids the intergranular oxidation that forms in traditional gas-atmosphere carburizing. Because it eliminates a known surface-quality defect and pairs naturally with high-pressure gas quenching using helium or nitrogen, the process and equipment claims around it are distinct enough from conventional carburizing to form their own filing cluster. This dataset's search string was built specifically around those distinguishing terms — acetylene boost-diffuse cycles, intergranular oxidation, and quench-gas choice — rather than generic heat-treatment language.
The ranked field covers 16 companies, with the top assignee holding 16 records against a fifth-place count of 2 and a tenth-place count of 1. That is a steep drop after the leader, meaning most of the ranked companies hold only one or two records each. Recent-year momentum data shows even the top assignees recording zero filings in the latest year, which is consistent with the wider filing slowdown visible since the 2018 peak.
The trend data shows filings rising to 12 in 2018 from 4 in 2017, then falling in subsequent years toward 2026. This dataset does not include a stated growth rate or cause for the decline, so any explanation beyond the raw counts would be speculation. It is worth noting that publication lags filing by roughly 18 months, so the last one or two years in the trend are understated regardless of the earlier decline.
CA2364356A1, filed by Praxair Technology, Inc., describes apparatus and a process for recycling a quenching gas such as helium alongside a treating gas such as a carburizing gas, for use in an atmospheric furnace. Its related family members, EP1211329A2 and US20020104589A1, are the two most-cited records in this entire dataset, at 25 and 17 citations respectively. Anyone designing a gas-recycling loop for high-pressure quenching should review this family closely before finalising equipment claims, since later filers in this space appear to have built on it.
The classes with the fewest records in this dataset are C22F (non-ferrous metal treatment) and H01M (batteries, cells and fuel cells), each at 1 record, followed by F27B (furnaces and kilns) at 2 and F27D (furnace details and accessories) at 3. These low counts, against a background where C23C and C21D together cover most of the corpus, suggest that furnace-hardware refinements and non-ferrous or battery-component applications of the core process remain comparatively open for new claims.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.